Buttonhole-sewing machine



J. FOSSA.

BUTTONHOLE sewmc MACHINE.

APPLICATION FILED JUNE 10, l9l5- Patented Mar. 15, 1921.

UNITED STATES IZATENT OFFICE.

JOSEPH rossA, on NEW Yonx. n. Y., assic'rnon, BY MESNE ASSIGNMENTS, TO UN snon MACHINERY CORPORATION, 01" rarnnson, new JERsEnA CORPORATION OF NEW JERSEY.

BUTTONHOLE-SEWING MACHINE.

Application filed June 10, 1915.

' enable others skilled in the art to which it appertains to make and use same.

The invention relates to buttonhole sewing machines in which overseam stitches are formed about the edge of the buttonhole by the cooperation of upper and under thread mechanisms. and more particularly to an under thread tension mechanism for such machines.

In doing certain classes of work it is desirable to use comparatively heavy tension on the under thread so that the purl may be brought to the upper side of the worln and in some cases the desired tension may be heavy enough to interfere with the proper feed of the work between successive buttonholes.

It is the object of the present invention to provide novel and improved mechanism for automatically releasing the tension on the under thread at the end of the sewing so that the work may be easily moved without danger of breaking the thread or injuring the under thread handling devices and for automatically reai')plying the tension at the beginning of the sewing. To this end the invention consists in the features of construction and combinations cit parts hereinafter described and referred to in. the claims.

The invention will be readily understood from an inspection of the accompanying drawings and the following detailed description of the mechanism illustrated therein.

In the drawings: Figure 1 is a vertical sectional view showing so much of a buttonhole sewing machine as is necessary to illustrate the application of the present invention thereto; Fig. 2 is a detail plan view showing the under-thread mechanism and a part of the clamp carrier; and Fig. 3 is a detail of the devices for automatically con trolling the tension for the under thread.

In the drawings the invention is shown as embodied in a buttonhole sewing machine Specification of Letters Patent.

Patented M a1".

Serial No. 33,374.

having substantially the construction and mode of ope'ation oil the machine shown and described in Patent No. 1,063.880. dated June 3. 1913. In this machine the stitch forming mechanism comprises an upper needle 2 eccentrically mounted in a verticallv reciprocating needle bar 4:, an under needle e, and a looper e. The upper needle bar is mounted in a rotary carrier 10 and the under needle and looper are mounted in a lo tary turret l2, thecarrier and turret being rotated during the sewing about the end and eye of the buttonhole. The work is held by clamps 14 mounted on supporting plates 16 which are in turn mounted on a clamp carrier 18. The clamp carrier is moved longitudinally of the buttonhole to bring the work from cutting to sewing position and to feed the work during the sewing by a cam groove formed in a cam gear 22 which makes one revolution for each cycle of the machine. The clamp carrier is moved laterally and the stitch forming mechanism is rotated during the sewing through suitable connections from a gear 24; which makes one revolution. during the sewing of a buttonhole.

The tension mechanism for the under thread comprises two tension disks 26 mounted upon the turret and pressed together by a spring 28. the tension of which may be varied by an adjusting nut 30. The mechanism for controlling the tension on the under thread comprises a tension releas iug le er 32 pivoted upon the tur et and having a wedge-sh aped lower end adapted to pass between the tension disks and separate them so as to release. the tension on the thread. The upper end ot' the lever 32 is curved to project over the upper edge of the turret and is provided on its outer end with an inclined cam surface 34 adapted to be engaged by a finger 36 projecting from the end of the clamp carrier. The under thread leads up through the hollow link 38 which forms a part of the mechanism for actuating the under needle and looper between the tension. disks through a. thread guide 40 on the turret. through a thread guide 42 on the. under needle arm. and thence to the needle.

When the machine is at rest the work clamp is in position to register with the buttonhole cutter 441 and the finger 36 is held in engagement with the end of the lever 32 so that the lower end of the lever is pressed between the tension disks and thread. The pressure of the disks'on the inclined surfaces at the end of the lever may force the end of the lever from between the disks, or the lever may be withdrawn by the weight of its upper end when the finger 36 withdraws from engagement with the upper end of the lever. At the completion of the sewing, the rotation of the turret is arrested with the turret in the position indicated in Fig. 2 and the turret remains in this position until the beginning of the next succeeding sewing operation. After the sewing of the buttonhole has been completed the clamp carrier is retracted to bring the work clamps again into register with the cutter and during this movement of the clamp carrier the finger 30 again engages the end of the lever 32 and operates the lever to relieve the tension on the under thread so that the under thread offers little or no resistance to the withdrawal of the work or its movement into position for the cutting and sewing of the succeeding buttonhole.

Having explained the nature and object of the invention and specifically described one form of mechanism in which it may be embodied, what is claimed is 1. A buttonhole sewing machine, having in combination, stitch forming mechanism comprising upper and under thread mechanisms, a rotary turret carrying the under thread mechanism, a longitudinally movable. work clamp carrier, an under thread tension device on the turret, a tension controlling lever mounted on the turret, and a finger on the carrier arranged to be engaged with and disengaged from the lever by the reciprocation of the carrier.

ing means a movement relative to each other in the vplane of the work, a rotary turret carrying the under thread mechanism, a tension device for the under thread mounted on the turret, and means rendered operative by such relative movement of the stitch-framing mechanism and worlnholding means to release the tension on the under thread at a predetermined point in the cycle of operations.

3. In a buttonhole sewing machine, the combination with work-holding means, of

stitch-forming mechanism comprising means I for manipulating both an upper and an under thread, a rotary turret carrying the under thread mechanism, means to give the worlcholding means and stitch-forming mechanism a relative movement during the stitching operation on a buttonhole, and a further movement after the stitching operation has been completed to carry the parts from stitching to buttonholecutting position, a tension device for the under thread mounted on the turret, and means operative during such further relative movement to render the tension device inoperative,

4. In a buttonhole sewing machine, the combination with work-holding means, of stitch-forming mechanism comprising means for manipulating both an upper and an under thread, a rotary turret carrying the under thread mechanism, means to give the stitch-forming mechanism and workholding means a relative movement in the plane of the work before, during and after the stitching operation on a buttonhole, a tension device for the under thread mounted on the turret, means operative during the relative movement before the stitching operation to apply the tension on the under thread, and means rendered operative by the relative movement after the stitching operation to release the tension on the under thread.

, JOSEPH FOSSAV 

